A battery monitoring IC with an isolated communication interface for electric vehicles

Abstract

This paper presents a Li-ion battery monitoring and protection IC suitable for monitoring 12 battery cells for electric vehicles (EVs). A two-wire, transformer based, isolated interface is proposed to provide the interface for the cascaded ICs. The interface uses the “balanced” two-wire technology and encodes the four SPI signals into DC-free pulse that can be coupled by a transformer, which features high-speed, low electromagnetic interference (EMI), and reliable data transmission. The IC was fabricated in a 0.18 µm, 60 V BCD process, with a total chip area of 4.4 × 3.6 mm². Measurement results show that the proposed interface can achieve a data rate up to 1 Mbps. Meanwhile, the measured current consumption is less than 45 µA in sleeping mode.